The discussion involving Judith Curry and The Hockey Stick Illusion has continued at Collide-a-Scape, with posts on the views of Judith Curry (Curry did admit to getting one of her ten points wrong, but not the other nine) and those of Gavin Schmidt.
Steve McIntyre’s comments in the second thread provides another case where readers can judge the reliability of his claims without having to delve into the mathematics. He wrote:
The non-Stickness of Mann-style reconstructions without bristlecones+Gaspe or with reduced bristlecone+Gaspe weight – a point conceded by Wahl and Ammann – was inconsistent with MBH98 claims that their results were “robust” to the presence/absence of dendroclimatic indicators. MBH98 stated that “the long-term trend in NH is relatively robust to the inclusion of dendroclimatic indicators in the network”,
But if you look at the paper you’ll see what they actually said:
“But certain sub-components of the proxy dataset (for example, the dendroclimatic indicators) appear to be especially important in resolving the large-scale temperature patterns, with notable decreases in the scores reported for the proxy data set if all dendroclimatic indicators are withheld from the multiproxy network. On the other hand, the long-term trend in NH is relatively robust to the inclusion of dendroclimatic indicators in the network,suggesting that potential tree growth trend biases are not influential in the multiproxy climate reconstructions.”
So in fact they said that dendro was “particularly important” for large-scale temperature patterns. What they said was “robust” was just the “long-term trend”.
It gets worse. McIntyre continued:
a point made even more forcefully in a note to Mann et al 2000, which stated:”Whether we use all data, exclude tree rings, or base a reconstruction only on tree rings, has no significant effect on the form of the reconstruction for the period in question.
What do you think “the period in question” refers to? McIntyre has artfully removed that sentence from its context to make it look like Mann is making a claim about the period from 1400 to the present. But look at the sentence in context.
NH temperature reconstructions based on all records, and on subsets excluding or comprising exclusively of, tree-ring data.
Note that the NH reconstruction based on the sparse “non-dendro” multiproxy network (19 non-dendro indicators available back to 1760) is remarkably similar to that based on the full (more than 100 indicators) multiproxy network of MBH98. Because the sampling of the “no-dendro” dataset is much sparser, we expect that it will be more influenced by regional variations, and less representative of the true NH mean temperature. Accordingly, it calibrates significantly less (47% vs. 74%) of the instrumental NH variance, and the variability and uncertainty in the reconstruction is larger. Nonetheless, the overall variation–and the long term trends in particularly–are remarkably similar. Also shown is the reconstruction based ONLY on dendroclimatic indicators (ie, no coral, ice core, or historical or instrumental indicators). Again, the primary features of the reconstruction are very similar. Whether we use all data, exclude tree rings, or base a reconstruction only on tree rings, has no significant effect on the form of the reconstruction for the period in question.
The “period in question” is from 1760 to the present, not 1400 to the present as McIntyre pretends.
You don’t have to take my word for any of this — check it out for yourself and ask yourself if you can trust the claims McIntyre makes about things that aren’t so easy to check.